x11perf -all leads to Xorg crash on 8-STABLE

[Carlos A. M. dos Santos]

On Sun, Dec 27, 2009 at 3:22 PM, Robert Noland <rnoland at freebsd.org> wrote:
> On Sun, 2009-12-27 at 15:17 -0200, Carlos A. M. dos Santos wrote:
[...]
>> I figured out that "x11perf -shmputxy10" triggers the crash. Mys first
>> guess was that something related to shared memory was causing the
>> problem. However, running the X server with
>>
>>      truss /usr/local/bin/Xorg >& Xorg.truss.log
>>
>> shows that all shm* calls succeed. Anyway, I attempted to increase the
>> available shared memory, using the values recommended by the Xine
>> port:
>>
>>      sysctl kern.ipc.shmmax=67108864
>>      sysclt kern.ipc.shmall=32768
>>
>> But it keeps crashing.
>
> Attaching gdb to X and getting a backtrace and/or enabling drm debugging
> is more likely to point to the issue.

How do I enable drm debugging?